On September 19, 1910, Thomas Jennings, who had just gotten out of jail six weeks earlier, entered the Chicago home of Clarence Hiller, intent on robbing the place. But Hiller’s wife awoke and screamed, alerting her husband to the intruder. A fight ensued and shots were fired. Hiller lay dead and Jennings fled the scene. But he left behind one important clue that would eventually lead to his murder conviction…a fingerprint. Jennings’ trial was the first one in the United States in which a fingerprint, a new technology, was used as evidence. Let’s look at the trial and the history of fingerprinting.